Today, I take time to discuss another general type of ammunition, shotgun cartridges. I will discuss shotgun shell components and shell sizes.

Shotgun shells have similar components to rifle cartridges, except internal to the shell there is one more component. The components of a shotshell are:

The shot or slug

The case

The Wad

Gunpowder

The Rim

The Primer

Hopefully you will know what the case, gunpowder, rim and primer are by now, but just in case you havent read my rifle ammunition components post, I will rehash.

The primer is the little explosive center of the shell. It is hit by the firing pin in the shotgun and has a percussion that ignites the powder.

The gunpowder is a fast burning, not exploding, material in the shell that creates gas expansion in the shell. This provides the necessary propulsion for the shot.

The shell case, much like the rifle cartridge case, is what houses everything. The “gauge” of a shotgun is based on a sphere of lead with the diameter of the bore was a fraction of a pound. So a 12 ga would be 1/12 of a pound and a 20 ga would be 1/20 of a pound. This goes back to cannon shot days. So a smaller number would be closer to a pound, thereby a larger bore (inside of barrel).

10, 12, and 20 ga are the most common shotguns, with the .410 bore (think caliber… also 10mm) is probably the most common small shotgun. There are also shotguns available in 4, 8, 16, 24, 28, and 32 gauges that are either not common, or considered obsolete. The 10 ga is also going “out of style” since the lengthening and strengthing of 12 ga shells.

There are also different shell lengths like 2 3/4, 3, 3 1/2 inch shells (which are the most common). Shotguns will tell you the chamber length, so you don’t place the incorrect length of shotshell in it.

The rim is just basically for the action of the shotgun and for keeping the shell chambered correctly.

The wad is made up of either three individual parts, or is designed to have all three parts in one wad.

The Gas Seal

The Cushion

The shot cup

The gas seal is designed to keep the expanding gas behind it so that the full force of expansion is felt in the forward motion.

The cushion is a shock absorber to prevent the sudden violent expansion of gas from deforming the shot. It also is placed in the shell at various sizes to take up any free space between the powder and shot, keeping everything tight. They are often designed with a “crumple zone” and are usually made of plastic, although fiber wads are available when desired.

The shot cup is designed to to house the shot and keep it together as it travels down the barrel. It has slits down the side to allow it to tear away from the shot the instant it leaves the barrel, so the shot travels freely.

The shot or slug comes in many sizes and variants. I don’t want to discuss shot sizes today. I also don’t want to go into detail about the slugs beyond just a list of types of slugs.

Basic shot types are birdshot and buckshot, which I will cover later. Basic slug types are the Brenneke, Foster, Sabot, and Wad slugs. I am not going to spend too much time in the future discussing the wax slugs or cut shell slugs of the great depression era.

Beyond the “pumpkin ball” slugs, pretty much all of the other lead slugs are rifled on the slug to provide some stable spin to raise the range.

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Ken is addicted to fitness and mountain biking. He is such a thrill seeker, people are starting to be concerned!He enjoys MTBing, Hiking, Climbing, Geocaching, Orienteering, Weight Lifting, and Wilderness Survival.